TP53 is a transcription factor that exerts tumor suppressor function by regulating the cell cycle, DNA repair and apoptosis. Its transcriptionally active form is a homotetramer consisting of four identical monomeric units. Somatic mutations in the p53 gene are found in over 50% of human cancers and germ line mutations in p53 are responsible for an inherited cancer predisposition, Li-Fraumeni syndrome. In addition, for those cancer cells that lack a p53 mutation, up to 80% exhibit a 5-10-fold reduction of p53 protein levels compared to corresponding normal tissues. It has been proven that by supplement p53 protein in these p53-difficient cancer cells to their normal level, the cells will undergo apoptosis and tumors can be controlled or eliminated. Our innovative approach involves the development of a p53 fusion protein therapeutic using our unique, patented refolding technology, Pt-Fold, in conjunction with an efficient, specific, peptide-based delivery technology. During the SBIR Phase I funding period, we have refolded the wild-type, full-length p53 as well as a fusion protein, gonadotropin-releasing hormone-p53 (GnRH-p53), in a stable tetrameric form, from E. coli inclusion bodies. In addition, we have demonstrated a proof of the concept that GnRH-p53 binds to GnRH receptors on the cell surface, enters the cell nuclear, and inhibits the growth of cancer cells in vitro. In preliminary animal studies using rodent tumor models, our university collaborator demonstrated that the GnRH-p53 tested was capable of dramatically slowing tumor growth when compared to controls. In the Phase II project, we will further develop the GnRH-p53 therapeutic into various preclinical dosage forms for therapeutic application. The long term objective of this study is to develop GnRH-p53 into an effective antineoplastic drug to treat patients with breast, ovarian, and prostate cancers. PUBLIC HEALTH RELEVANCE: This project is to develop new process for efficiently producing GnRH-p53 protein therapeutic for scale-up production and formulation development. The ultimate goal is to develop GnRH-p53 into an effective antineoplastic drug to treat patients with breast, ovarian, and prostate cancers.